1. Field of the Invention
This invention relates to body exercising apparatus and more particularly to weight exercise machines that provide a substantially uniform resistance throughout the range of motion of each of several different kinds of weight lifting exercises.
2. Background Art
Weight lifting exercises have long proven effective for muscle and general body building. For a weight trainee who is a trained athlete or who has otherwise acquired adequate strength and muscle conditioning, bar bells and dumbbells can be used in performing bench presses, leg squats, biceps curls, triceps extensions and other weight training exercises. Bar bells and dumbbells, however, can inadvertently fall or be dropped, possibly resulting in bodily injury or property damage; and, the danger of their falling or being dropped is higher when used by new and unconditioned weight trainees. A variety of weight training devices that substantially eliminate that danger while at the same time simulating the lifting of a barbell or dumbbells have been disclosed, of which the following references are exemplary: U.S. Pat. No. 458,382 to Zander; U.S. Pat. No. 2,93,509 to Zinkin; U.S. Pat. No. 4,093,213 to Coker et al.; U.S. Pat. Nos. 4,211,403 and 4,226,414 to Coffaro et al.; U.S. Pat. No. 5,358,462 to Calderone; U.S. Pat. No. 5,788,616 to Polidi; U.S. Pat. No. 5,688,216 to Mauriello; and U.S. Pat. No. 6,361,481 B1 to Koenig. These and similar weight training devices of the prior art provide a body-engaging means attached to a first end of a pivot arm or lever, means for pivoting the lever, and weight resistance means attached to a second, opposite end of the lever, with the result that, as a weight trainee moves the body-engaging means through the range of motion of a selected weight lifting exercise, the degree of resistance the trainee experiences varies through the range of motion of the exercise, and generally not in any optimal way. This problem was addressed by Mahnke in U.S. Pat. No. 4,546,970, who disclosed a weight type exercising device wherein the effective length of the lever arm is changed during the range of motion of a weight lifting exercise so as to continuously vary the resistance through the range of motion in a way considered by Mahnke to be closer to optimal. In U.S. Pat. No. 5,529,558, Koenig disclosed a weight lifting device, specialized for squatting and heel raising exercises wherein the body-engaging means was a pair of padded shoulder bars mounted to a first end of a pivot arm, weight suspending means being affixed to an intermediate portion of the pivot arm, and the pivoting arm rose up and down a pivotable mast. The effective length of the pivot arm was thereby varied such that the resistance experienced by the weight trainee at the bottom of a squat was minimized and the resistance increased as the trainee moved the body-engaging means upward and rose to a standing position. This variation in experienced resistance was considered desirable by Koenig because the effective leg strength of the trainee is least at the bottom of a leg squat.
The exercise devices of Mahnke and of Koenig do not satisfactorily solve the problem presented, however. Many weight lifting devotees, especially those who engage in competitive weight lifting competitions, prefer to experience uniform resistance throughout the range of motion of each weight lifting exercise because that best simulates what is experienced when one is actually lifting barbells and dumbbells. Moreover, the devices of Mahnke and Koenig can only be used for a relatively few kinds of weight lifting exercises; they are not suitable, for example, for triceps extensions or arm curls. What is particularly desired, and what Mahnke and Koenig have failed to provide, is a single weight exercise device that is designed to train every body part and upon which as many as forty weight lifting exercises can be performed, and through which device a weight lifting trainee experiences substantially uniform resistance throughout the range of motion of each exercise.